Heat exchanger



ec. 1, 1953 R. A. SANDBERG HEAT EXCHANGER Filed Feb. 8, 1950 JHVEJYL UP53: Eag M5az2dbezg Z HLi E Patented Eec. l, 1953 HEAT EXCHAN GER Bay A.Sandberg, Waukegan, Ill., assignor to Houdaille-Hershey Corporation,Detroit, Mich., a corporation of Michigan Application February 8, 1950,Serial No. 143,010

Claims. (Cl. 257-256) The present invention relates to a heat exchangerand to a method of making the same. More particularly, the presentinvention relates to a heat exchanger of the plate and tube typeprovided with means for greatly increasing the effective area of theexchanger, and to a method for making such an exchanger.

Tube and plate type exchangers of the prior art typically comprise aheat conductive backing plate on which a continuous length of tubing issecured, as by brazing or welding, to provide a conduit for the flow ofheated or refrigerated fluid. In my copending application Serial No.80,240, filed March 8, 1949, now abandoned, and entitled Heat Exchangerand Method of Making the Same, I have disclosed the employment of abacking plate which is deformed into tightly gripping effective heattransfer relation with a tube to eliminate the necessity of a separatewelding or brazing step. Reference is also made to my copendingapplication Serial No. 206,531, filed January 18, 1951, disclosingcommon subject matter.

The present invention now provides an improved heat exchanger in whichthe effective heat exchange area of the unit is greatly increased whileat the same time maintaining highly efficient heat transfer contactbetween the plate surfaces and the exchanger tube.

More particularly, the present invention contemplates the provision of amain backing plate of good heat conductive properties and an auxiliaryheat conductive plate having spaced elongated portions secured to thebacking plate and intermediate portions spaced from the backin plate toprovide an additional heat exchange surface. The heat exchanger tube issecured in the assembly at the area of contact between the two heatconductive surfaces, so that effective heat transfer between the tubeand each of the heat conductive members is attained. In addition, thesecooperating heat conductive members provide channels or stacks for theflow of a gaseous medium, such as air, into contact therewith toincrease the heat transfer efficiency of the unit.

The method of the present invention contemplates the formation ofelongated spaced parallel grooves in contacting portions of the main andauxiliary plate members, the positioning of a tube within the grooves,and the deformation of each of the plate members to overlie a mediandiameter of the tube portions bottomed in the grooves to securely lockboth of the heat dissipating members andthe tube into a secure,thermally efficient assembly.

The advantages of the present invention reside in the increasedefficiency of the exchanger due to the effective channeling of thegaseous medium to be heated or cooled and to the effective heat transferrelation between the tube and each of the plate members.

It is, therefore, an important object of the present invention toprovide an improved heat exchanger of the plate and tube type having agreatly increased heat exchange area.

Another important object of the present invention is to provide animproved method of making a heat exchanger by the securing of a tube tothe exchanger by the deformation of a plurality of plate members intogreater than semi-peripheral contact with the tube.

A further important object of the present invention is to provide animproved heat exchange panel including a pair of plate members and atube secured to the members in effective heat transfer relation, theplate members cooperating to define therebetween gaseous flow passagesand a heat transfer surface of increased area.

It is still another important object of the pres ent invention toprovide an improved method for making a tube and plate type heatexchanger including the steps of grooving a pair of heat conductiveplates, positioning a heat exchange tube in the grooves thus formed, anddeforming grooved portions of both of the plates to overlie a mediandiameter of the tube, thereby interlocking the tube and the plates intoa thermally eificient assembly.

Other and further important objects of this invention will be apparentfrom the disclosures in the specification and the accompanying drawings.

On the drawings:

Figure l is a plan view of a heat exchanger of the present invention;

Figure 2 is a fragmentary, enlarged sectional view taken along the planeII-II of Figure l and Figure 3 is a fragmentary, enlarged sectionalview, similar to Figure 2, illustrating a step in the method of makingthe heat exchanger of Figure 1.

As shown on the drawings:

In Figure 1, the reference numeral It! refers generally to a heatexchanger of the present invention including a sinuous tube ll havingstraight parallel portions 12 extending along the length of theexchanger [0 and arcuate portions l3 joining the straight portions [2and extending beyond the confines of the heat exchanger it.

In Figure 2, it will be seen that the straight 3 parallel portions I2 ofthe tube II are secured to a backing plate I4 and a supplementary plateI5. Both plates are formed of thin sheet metal having good thermalconductive properties, such as mild steel. The backing plate I4 isprovided with parallel marginal upstanding flanges I6 deformed from theplane of the plate Id. The flanges I6 are apertured as at H at spacedpoints along their length to facilitate assembly of the heat exchangerID in a desired position, as on a refrigerator or the like.

The supplementary heat conductive plate. I5, which is preferably oflighter gauge than the plate I4, is provided with parallel,longitudinally extending raised portions I8 which extend along thelength of the backing plate It between the flanges I6 and generallyparallel to the: flanges I6 and the tube straight portions I2. Theraised portions I8 of the member I are provided" with transverselyextending raised reinforcing ribs I9. The height of the. raisedportions: I281- is such that the. upper. surface of the ribs; is.displaced from the mean plane of the. plate I4: tov a distanceapproximately equal to or slightly less; than the height of the endflanges IS.

The auxiliary plate I5 is provided with inclined web portions joiningthe raised portions I8 to intermediate web portions 2| of the plate I5.The web portions 2| of the auxiliary plate 45 and a correspondingportion of the backing plate I4 are employed to lock the straight tubeportions I2 within the assembly as. hereinafter described.

The method of assembly (Figure 3) includes, first, the initialdeformation of each of the plates I4 and I5 to provide a plurality ofparallel, spaced depressions or grooves 22 and 23 in the plates I4 andI5, respectively. The grooves 22 and 23 have arcuate bottoms 22a and23a, respectively, and upstanding parallel side walls. 22b and 231),respectively. The grooves 22 and 23 may be formed simultaneouslyfollowing the positioning of the supplementary plates I5 upon thebacking plate It, or the grooves. may be separately formed in each. ofthe plates; for. registry upon initial assembly. In any event, each ofthe I grooves extends uniformly along. the length of the respectiveplates so that. upon assembly; the coextensive grooves 22 and 23. arenested,. as shown in. Figure 3.

The straight tube portions I2. are inserted in the grooves 23 which, inturn, are nested in the grooves 22. The radius of curvature ofv the.-arcuate bottom 23a of the groove 23. is. substantially that of theexterior surface of. the: tube. while the radius of curvature of. theinterior surface of the groove 22 is substantially that of the exteriorsurface of the groove 23 so that smooth mating engagement is attained.It' will also. be noted that the depth of the groove 23. issubstantially greater than. the diameter: of the tube II.

It will be seen that only the straight portions I2 of the tube II are.bottomed within the groove 23. This eliminates the necessity of formingsinuous grooves in the plates I4 and I5, inasmuch as the arcuate joiningportions L3 of the tube II are allowed. to project beyond the sideextremities of the plates I4 and I5 of the finished exchanger I0.

The securing of the tube II to the plates I4 and [5 within the grooves.22 and 23- may be carried out by means of apparatus such as thatillustrated in the above-identified copending application or by othersuitable means for swaging or otherwise deforming the upstanding sidewalls 221) and 23b of the grooves 22 and 23, respectively, to overlie amedian diameter of the straight tube portions I2. This deformation ofthe grooved side walls may be carried out by either a rolling or astamping operation. As a result of the deformation of both plates, themating portions of the plates I4 and I5 are deformed to overlie greaterthan semi-peripheral portions of the tube I2. The deformation is suchthat a pair of additional grooves 25 and 25 are formed alongside of andparallel to the main grooves 22 and 23 in the plates I4 and I5,respectively. These additional or supplementary grooves 24 and 25. arecontiguous to and coextensive with the lengths of the main grooves 22and 23, and metal intermediate the supplemental grooves and the maingroove of each plate is actually deformed inwardly of the tube tooverlie the tube I2, as at 2B and 21.

The area of contact. of the plates I4 and I5 is coextensive withthe areaof the. grooves. 22 and 25 of the backing plate I4 and the area of thegrooves 23 and 25 of theplate l5- The con.- tact area thus includes themetal of; the plates I4 and I5 partially surrounding the. tube I2- andthe immediately contiguous. plate areas. of the supplemental groovesformed: on; interlocking the plates andthe grooves.

There is no actual surface. contact between the backing plate. I4 andthe tube. portion; I52: However, the backing plate portions 26 are de--formed so as to overlie. a median diameter" of the tube, thereby lockingthe. plate through. the tube in a firm interlocking engagement. Tl'xesesame interlocking portions 26; of the plate. H3; in combination withthetube: portions I2. secure the auxiliary plate IE to the plate. I 4.

Upon the assembly of the: heat exchanger. Ii] in operative position, as,for instance, supported upon the back surface of a. refrigerator or thelike, with the' parallel lengths: of tubing extending vertically, thesupporting. surface cooperates with the ribs I9 formed on the raisedauxiliary plate portions It to defln'etherewith azplurallty of channelswith the: tube portions I2. in one; of the channel walls. Also, theraised. portions; [8 andthe backing plate I4 cooperate todefineadditionalchannels therebctween. The raised. ribs I 9 not onlyserve to reinforce the. raised portions I8 of the plate I4 but theseribs'serve: to space the raised portions. [8 from a supporting surfacesothat minimum interferencewith heat transfer from theportion If)isolfered; It. will be seen that the auxiliary heat exchanger plate I5serves to divide air flow between the flanges I6 into a plurality ofdifferent columns'or stacks. Thus, each side of the-surfaces I8: and20,.and those surfaces of the auxiliary plate overlying the backingplate, may effectively serve. as heat dissipation surfaces. In addition,those surfaces of the backing plate I i underlying the raised portionsI2 of the plate Iii alsoserve. as heat dissipating surfaces. Theauxiliary plate. thus more than doubles the effective heat dissipatingsurface ofthe heat exchanger. The channeled separation of air or othergaseous coolant: also increases air circulation and turbulence, so thatall of the coolant mediumis effectively employed.

It will be understood that modifications and variations may be efiected.without departing from the scope of the novel concepts of the presentinvention,

I claim as my invention:

1 The method of. making a heat. exchanger which comprises forming a pairof parallel grooves in a first metal plate spaced a preselected extentof the first plate apart, forming a pair of parallel grooves in a secondmetal plate spaced a preselected extent of said second plate apart, saidlast mentioned extent being greater than said first mentioned extent andwith respective grooves of said first and second plates nesting onewithin the other, bottoming a tube in the inner of said nesting grooves,and deforming the side walls of each of said grooves and intermediatecontiguous portions of each of said plates radially inward of the tubeto overlie a median diameter of said tube, thereby securely locking thetube in said grooves and said plates to one another in efficient heattransfer relation.

2. A heat exchanger comprising a backing plate, an auxiliary platehaving spaced portions contacting said backing plate and intermediateoffset portions forming a coolant flow channel therebetween, and asinuous tube for confining a flowing heat exchange fiuid having portionssecured within coextensive nesting grooves formed in contacting portionsof said auxiliary plate and said backing plate, said tube being ingreater than semi-peripheral surface contact with said auxiliary plateand in efficient heat transfer relation with both said auxiliary plateand said backing plate.

3. A heat exchanger comprising a backing plate having a plurality ofelongated parallel grooves extending thereacross, an auxiliary platealso having a plurality of grooves extending thereacross and nestedwithin the grooves of said backing plate in surface contact therewith,said auxiliary plate having portions intermediate the grooves thereinspaced from corresponding portions of said backing plate and a sinuoustube seated in said nesting grooves and secured therein by being ingreater than semi-peripheral surface contact With the grooves of saidplates.

4. A heat exchanger comprising a sinuous tube having straight parallelportions joined by arouate intermediate portions, a first heatconducting plate having spaced grooves receiving the straight paralleltube portions with said arcuate intermediate portions of the tubeextending beyond said first plate, said grooves being in greater thansemi-peripheral surface contact with said tube to secure the samethereto, and a heat conductive backing plate having parallel spacedgrooves eX- tending thereacross receiving the grooved portions of saidfirst plate coextensive and interlocked therewith to secure said backingplate to said first plate, said plates having other portions spacedapart to define coolant flow passages therebetween intermediate thestraight portions of said tube.

5. In a heat exchanger including a backing plate having parallel spacedgrooves, a sinuous tube having parallel portions secured within saidgrooves, an auxiliary heat dissipating plate comprising spaced parallelgroove portions nesting with the grooves of said backing plate andinterposed between said backing plate and said tube, said groovedportions being interlocked with said backing plate in effective heattransfer relationship therewith and in extended surface contact withsaid tube, and said auxiliary plate having additional portionsintermediate said grooved portions offset from the plane of said backingplate and cooperating therewith to define a gas flow passage.

6. A heat exchanger comprising a backing plate, an auxiliary platehaving spaced portions contacting portions of said backing plate and anintermediate ofiset portion forming with said backing plate a coolantflow channel, said backing plate and said auxiliary plate havingelongated nesting grooves in the contacting portions of said auxiliaryplate and said backing plat-e, and a tube for confining a flowing heatexchanger fluid, said tube having portions secured within said elongatednesting grooves in efficient heat transfer relation with both saidauxiliary plate and said backing plate.

'7. A heat exchanger for attachment to a substantially plane supportingsurface, comprising a thermally conductive metal backing plate havingend flanges for contacting said supporting surface, said flanges andsaid backing plate cooperating with said surfaces to define a primarycoolant fiow channel, an auxiliary plate having spaced portionscontacting portions of said backing plate and intermediate offsetportions forming with said backing plate a secondary coolant flowchannel, said backing plate and said auxiliary plate having elongatednesting grooves formed in the contacting portions of said auxiliaryplate and said backing plate, and a tube for confining a flowing heatexchanger fluid, said tube having portions secured within saidcoextensive nesting grooves in eficient heat transfer relationship withboth said auxiliary plate and said backing plate.

8. A heat exchanger for attachment to a substantially plane supportingsurface, comprising a thermally conductive metal backing plate havingend flanges for contacting said supporting surface, said flanges andsaid backing plate cooperating with said surface to define a firstcoolant channel, an auxiliary plate having spaced portions contactingportions of said backing plate and intermediate offset portions formingwith said backing plate a second coolant fiow channel, said contactingportions of said auxiliary plate and said tube backing plate havingelongated nesting grooves therein, and a tub-e for confining a flowingheat exchange fluid, said tube having portions secured within saidelongated nesting grooves in efficient heat transfer relation with bothsaid auxiliary plate and said backing plate.

9. A heat exchanger for attachment to a substantially plane supportingsurface, comprising a thermally conductive metal backing plate havingend flanges for contacting said supporting surface, said flanges andsaid backing plate cooperating with said surface to define a primarycoolant flow channel, an auxiliary plate having spaced portionscontacting portions of said backing plate and intermediate offsetportions forming with said backing plate a secondary coolant flowchannel, said backing plate and said auxiliary plate having elongatednesting grooves formed in the contacting portions of said auxiliaryplate and said backing plate, and a tube for confining a flowing heatexchange fluid, said tube having portions secured within said elongatednesting grooves and in efiicient heat transfer relationship with bothsaid auxiliary plate and said backing plate.

10. In a heat exchanger including a backing plate having parallel spacedgrooves, a sinuous tube having parallel portions secured within saidgrooves, an auxiliary heat dissipating plate hav ing a grooved portionnesting with one of said grooves of said backing plate and interposedbetween said backing plate and said tube, said grooved portions beinginterlocked with each other and with said tube portion secured thereinand in effective heat transfer relationship there- 7 with and u saidauxiliary plate h-atvingzprojeetinns extending from the plane oi'saidzbackingfplate and at a substantial angle thereto between; acljatcentgrooves and cooperating with said-backing plate 'to' increasetheiheatiexchangiemefi'lci'ency of the heat exchanger;

RAYA. SANDBERG;

ReferencesCited in thefile of thispatent UNITED STATES PATENTS NumberName Date.

1,707,655 Cohn ,Apr; 2,: 1929 Number Name Date Whitesel Dec. 8, 1936Brown Aug. 31, 1937 Steenstrup Apr. 28, 1942 Schoen July 14, 1942 HerterDec, 29, 1942 Lynn Nov. 11, 1947 FOREIGN PATENTS Country Date GreatBritain Jan. 4, 1934 GreatJB'ritain' Aug; 25, 1937

